I was picturing a swashbuckler/fighter who uses pistols. (High dex/int, lotsa skills, pistol's are light weapons and thus gain the swashbuckler's int to damage. Fighting defensively in light/no armour, quipping, etc.).
The reason swashbuckler's suck is b/c they're basically a dip class, (Similar to monks/paladins, except monk's and paladins have SOME reason to take more than a few levels). After level 3 they don't really have anything that I find fun. Dodge bonus +1(single target) every 5 levels? woohoo. Maybe if it were a flat out Dodge bonus to AC (and not single opponent), like monk.. And as for Grace and improved flanking..
The problem with Swashbucklers is that while a lot of their abilities make sense (Weapon Finesse, acrobatic charge, acrobatic skill mastery), they aren't very USEFUL.
Some of the higher level stuf, while powerful, either comes too late to be useful(slippery mind at lvl 17?), or is based off of Crits (weakening and wounding critical)... Meaning to make proper use of them you should be playing a 'crit character'.
My biggest problem is that they don't have a good END ability (Unless, as stated before, you're into crits, and I don't like playing crit characters b/c there's a good chance at high level that your opponent will be immune)
Personally what I'd do to it is drop grace, and instead give them a GOOD reflex save. Replace the dodge bonus with a +1/5 levels Dodge Bonus to AC and drop Improved Flanking for Uncanny Dodge at lvl 2, Improved Uncanny dodge at level 8.. (I never saw swashbuckling as focusing on one opponent, I picture people moving and fighting several foes, fencing with three opponents at a time.. you know, MOVIE swashbucklers).
NOW, at this point there's two ways to go.. If you want the swashbuckler to be a critical hit character, keep weakening/wounding critical, and add Improved Critical as a bonus feat at level 9.
Otherwise, i'd drop those two in favour of bonus feats or specific rogue special abilities(Defensive roll/Opportunist?) at levels 9, 14 and 19.
BTW, keep in mind that As it stands, Swashbuckler doesn't have any real 'dead' levels, because all the levels when they don't gain a class ability they either gain a feat or a stat point (4,6,9,12,16)